Session 7. Case studies of gene identification using FG tools

Chair: Mathew Morell                       Rapporteur : Xue-Rong Zhou

As the examples of using functional genomics tools to study gene function, four speakers presented their case studies in session 7.

Dr. Qianhao Zhu from CSIRO Plant Industry (Australia) reported the rice mutant defective in anther dehiscence (aid1 gene) by Ds transposon tagging. The mutant resulted in partial to complete spikelet sterility, and delayed panicle heading. The phenotype was not restored by jasmonic acid treatment at panicle booting and anthesis stage. The predicted sequence of aid1 around Ds tag has been analyzed, and the data also suggested possible relationship between aid1 and male sterile locus ms1. The speaker was asked that why the phenotypes ranging from partial to complete sterility. He suggested that there could be redundancy of the gene due to the complexity.

Dr. Marcia Margis from CSIRO Plant Industry (Australia) reported a Ds transposon tagged mutant showing GA sensitive strong dwarf phenotype. Molecular biology analysis indicated that Ds tagged in gene coding for ent-kaurene synthase (KS), which catalyze early step of the GA biosynthesis pathway. Questions include that whether there would be multigene family corresponding for same phenotype. The answer was that it is possible, while each gene expresses differently. Another question was that why the phenotype of mutant in terms of anthesis was not completely restored by GA treatment. The speaker suggested that it could be due to the possible factors such the penetration of GA into leaf, dosage of GA, or time of the treatment.

Dr. Hirohiko Hirochika from National Institute of Agrobiological Science (Japan) reported the functional analysis of MAP kinase genes in rice by retrotransposon. Mutants of five out of ten rice MAP kinase genes have been isolated by PCR screening, but only one mutant of one gene (OsMPK2) showed phenotype. He explained that this possibly due to gene duplication or screening conditions are not appropriate. While asked whether forward genetics can solve the problem linked to redundancy, he suggested that only reverse genetics would be possible to uncover the functions of redundant genes.

Dr. Chang-deok Han from Gyeongsang National University (Korea) reported current status of analysis of Ds flanking DNA. Over 3,000 Ds flanking DNA were identified by PCR, and over 500 clones were sequenced and analyzed for gene identification. He then described the examples such as tagged genes encoding receptor kinasae, expansin, zinc finger protein, photolyase, and some putative proteins, as well as resulted in some specific GUS reporter patterns.